WA energy policy 2026

State-level rebate that stacks with federal STCs for Synergy network (SWIS) customers:

• Synergy customers: $130/kWhup to $1300 (10 kWh cap)

Combined federal + state on a 10 kWh battery: up to $4,013. No-interest loan also available up to $10,000 with a $210,000 income cap. Min capacity: 5 kWh. VPP + Battery Rewards opt-in is a precondition.

If you already have a non-hybrid solar inverter and want to add a battery, you have three options. The gateway requirement is the key compliance pivot.

• Add an AC-coupled battery + SSL gateway. Cheapest upfront, hardest in practice. The gateway must be on the Synergy Supported Solutions List and support both your existing inverter and the new battery — and third-party gateways can struggle to meet the compliance requirements and complete testing. Without the gateway you default to Tier 0 (1.5 kW fixed export) and lose VPP / state rebate eligibility. Any later addition to an AC-coupled system triggers whole-of-site compliance, so expanding it down the track is difficult.
• Add a second hybrid inverter alongside. Useful if you want more solar capacity at the same time.
• Replace the inverter with a hybrid + DC-coupled battery. Most efficient long-term and, for many existing systems, the sounder path — it avoids the gateway and expansion limitations above, though it costs more upfront. Best if the existing inverter is near end of warranty.

Sungrow and Fronius support shared monitoring across paired inverters, which can satisfy whole-of-site compliance without a separate third-party gateway — though any later addition to the system still triggers whole-of-site compliance.